[reference-impl-sync] Reference Implementation sync: 34 new commits (2026-05-22)

[github-actions]

Automated Reference Implementation Sync

There are 34 new commits in the official Copilot SDK since the last merge.

• Last merged commit: f6c1adf8329ad4206e5ed2e8d12fb8082bc841a2
• Reference Implementation HEAD: f4d22d70016c377881d86e4c77f8a3f93746ffae

Recent reference implementation commits

f4d22d70 Add preMcpToolCall hook support to all SDKs (#1366)
311695e5 Update `@github/copilot` to 1.0.52-1 (#1371)
8ba75ec3 Update `@github/copilot` to 1.0.52-0 (#1370)
23526eba Bump org.apache.maven.plugins:maven-enforcer-plugin (#1365)
f4223c81 Add java to monorepo: Phase 02: code and test CI. (#1348)
cf0b3058 Go SDK API review fixes (#1360)
a205e690 Fix flaky pending-messages-modified E2E test across SDKs (#1362)
76168a84 TypeScript SDK API review fixes (#1357)
a815e741 Enable .NET E2E tests to run on .NET Framework (net472) (#1358)
c490d7af C# API review fixes (#1343)
ebac7594 Update `@github/copilot` to 1.0.51 (#1353)
1015e7af Update `@github/copilot` to 1.0.51-3 (#1351)
477834f8 Publish .snupkg symbols package to NuGet.org (#1345)
38ca0961 Make MCPStdioServerConfig.args optional across all SDKs (#1347)
0f4d7cea Add Rust (and C#) to SDK language lists across docs (#1349)
43d6aefe Fix flaky Should_Accept_Both_MCP_Servers_And_Custom_Agents test (#1346)
d6006756 Update `@github/copilot` to 1.0.51-2 (#1342)
20e165bd Update `@github/copilot` to 1.0.51-1 (#1340)
584a7901 Strip Ms suffix for duration properties (#1339)
ac85df17 Emit regex data annotations from C# codegen (#1338)

Instructions

You MUST follow these steps in order. Do NOT improvise or skip scripts.

1. ✅✅Read .github/prompts/agentic-merge-reference-impl.prompt.md in full before starting✅✅

❌❌Do NOT clone the reference implementation manually — the start script does this.❌❌
❌❌Do NOT update .lastmerge manually — the finish script does this.❌❌
❌❌Do NOT skip the finish script — it syncs codegen versions and updates .lastmerge.❌❌

Generated by Reference Implementation Sync · ● 2.3M · ◷

• expires on May 28, 2026, 3:42 AM UTC